The present invention concerns “port spoofing,” which allows a computer to “fail over” to its secondary fibrechannel connection if its primary fibrechannel connection should fail.
Fibrechannel is a network and channel communication technology that supports high-speed transmission of data between two points and is capable of supporting many different protocols such as SCSI (Small Computer Systems Interface) and IP (Internet Protocol). Computers, storage devices and other devices must contain a fibrechannel controller or host adapter in order to communicate via fibrechannel. Unlike standard SCSI cables, which can not extend more than 25 meters, fibrechannel cables can extend up to 10 km. The extreme cable lengths allow devices to be placed far apart from each other, making it ideal for use in disaster recovery planning. Many companies use the technology to connect their mass storage and backup devices to their servers and workstations.
In addition to being able to protect data through disaster recovery plans and backup, another requirement for a computer data communications network is that the storage devices must always be available for data storage and retrieval. This requirement is called “High Availability.” High Availability is a computer system configuration implemented with hardware and software such that, if a device fails, another device or system that can duplicate the functionality of the failed device will come on-line to take its place automatically and transparently. Users will not be aware that a failure and switch-over had taken place if the system is implemented properly. Many companies cannot afford to have downtime on their computer systems for any length of time. High availability is used to ensure that their computer systems remain running continuously in the event of any device failure. Servers, storage devices, network switches and network connections are redundant and cross-connected to achieve High Availability. FIG. 1 shows a typical prior art fibrechannel High Availability configuration.
In the configuration of FIG. 1, High Availability is achieved by first creating mirrored storage devices 145 and 150 and then establishing multiple paths to the storage devices which are represented by the fibrechannel connections 105, 110, 125, 130, 135, and 140. This configuration allows the server 100 to continuously be able to store and retrieve its data, even if multiple failures have occurred, as long as one of its redundant hardware components or fibrechannel connections does not fail. For example, if paths 110 and 125 fail, the data traffic will be routed through paths 105 and 140 to access storage device 150. Special software must be running on the server to detect the failures and route the data through the working paths. The software is costly and requires valuable memory and CPU processing time from the server to manage the fail-over process.